1. Field of the Invention
The present invention relates to the removal of oxygenated impurities from hydrocarbons such as isooctane and diisobutylene. More particularly, the present invention provides a process for producing diisobutylene and/or isooctane, which is substantially free of oxygenated contaminants, which contaminants if not removed interfere with the successful use of the hydrocarbons as internal combustion engine fuels.
2. Prior Art
The present invention is especially adapted for the production of high purity isooctane and/or diisobutylene from C.sub.4 hydrocarbon streams comprising substantial quantities of unsaturated butenes. A C.sub.4 stream containing unsaturated hydrocarbons can be obtained by cracking an appropriate saturated hydrocarbon stream or alternatively by dehydration of tertiary butyl alcohol which is co-produced in the Oxirane process. Technology is known for the dimerization of isobutylene from either source in high selectivity to produce diisobutylene and the subsequent hydrogenation of the diisobutylene to form isooctane. Illustrative of references demonstrating this particular art is Evans U.S. Pat. No. 5,877,372.
A disadvantage of prior procedures is that the diisobutylene and isooctane thus obtained contain small but significant amounts of oxygenated impurities. For example, the hydrocarbons may contain oxygenated impurities ranging from about 0.1 wt % to as much as 5 wt % of the isooctane or diisobutylene. Normally such oxygenated impurities are ethers, alcohols, acids, ketones and the like materials. The presence of oxygenated impurities in the diisobutylene or isooctane is undesirable in that these contaminants substantially decrease the utility of the diisobutylene or isooctane in internal engine combustion fuels such as gasoline blends.